Assessment of life history parameters of Aspidiotus nerii (Hemiptera: Diaspididae) to improve the mass rearing of Aphytis melinus (Hymenoptera: Aphelinidae)

The biological control of Aonidiella aurantii (Maskell) on citrus can be achieved with periodic releases of the parasitoid Aphytis melinus DeBach. A. melinus is normally reared on parthenogenetic strains of the scale Aspidiotus nerii Bouché. The developmental rate, crawler production and survival of A. nerii were studied at two temperatures (25±1 and 30±1°C) and two levels of relative humidity (RH; 55±5 and 85±5%) on squash. Temperature had an important effect on developmental rate, but RH did not. At 30°C, no growth was observed and no crawlers were produced. At 25°C, development of the L1, L2 and young females’ stages required 24.4±0.7, 11.1±0.8 and 13.2±0.3 days, respectively. At 25°C, times until the appearance of mature females, the start of crawler production and the peak of crawler production were 48.7±0.1, 50.1±0.7 and 63.3±1.0 days, respectively. Crawler production lasted 42.6±1.9 days, and the 50% production level was reached on day 13. Initially, crawler survival was higher at 30°C (65.9±2.8%) than at 25°C (51.7±4.8%), but by the end of development survival was much higher at 25 than 30°C (88.0±2.1 vs. 22.9±2.7%). RH had no effect on either initial or final survival. Average progeny production was of 28.0±2.8 crawlers per female at 25°C. The relationship between the weight of groups of crawlers and their number was: Number=1031+835,500×weight of group (g) (R ²=0.826), which can assist in colony management. The importance of selecting the correct strain of A. nerii is emphasised.     

The mitogenome of Halotydeus destructor (Tucker) and its relationships with other trombidiform mites as inferred from nucleotide sequences and gene arrangements

The redlegged earth mite, Halotydeus destructor (Tucker, 1925: Trombidiformes, Eupodoidea, Penthaleidae), is an invasive mite species. In Australia, this mite has become a pest of winter pastures and grain crops. We report the complete mitogenome for H. destructor, the first to represent the family Penthaleidae, superfamily Eupodoidea. The mitogenome of H. destructor is 14,691 bp in size, and has a GC content of 27.87%, 13 protein‐coding genes, two rRNA genes, and 22 tRNA genes. We explored evolutionary relationships of H. destructor with other members of the Trombidiformes using phylogenetic analyses of nucleotide sequences and the order of protein‐coding and rRNA genes. We found strong, consistent support for the superfamily Tydeoidea being the sister taxon to the superfamily Eupodoidea based on nucleotide sequences and gene arrangements. Moreover, the gene arrangements of Eupodoidea and Tydeoidea are not only identical to each other but also identical to that of the hypothesized arthropod ancestor, showing a high level of conservatism in the mitogenomic structure of these mite superfamilies. Our study illustrates the utility of gene arrangements for providing complementary information to nucleotide sequences with respect to inferring the evolutionary relationships of species within the order Trombidiformes. The mitogenome of H. destructor provides a valuable resource for further population genetic studies of this important agricultural pest. Given the co‐occurrence of closely related, morphologically similar Penthaleidae mites with H. destructor in the field, a complete mitogenome provides new opportunities to develop metabarcoding tools to study mite diversity in agro‐ecosystems. Moreover, the H. destructor mitogenome fills an important taxonomic gap that will facilitate further study of trombidiform mite evolution.     

Virulence of Hessian fly (Diptera: Cecidomyiidae) in the Fertile Crescent

The Hessian fly, Mayetiola destructor (Say), is an important insect pest of wheat (Triticum spp.) in North Africa, North America, southern Europe and northern Kazakhstan. Both wheat and this pest are believed to have originated from West Asia in the Fertile Crescent. The virulence of a Hessian fly population from Syria against a set of cultivars carrying different resistance genes, in addition to other effective sources with unknown genes, was determined in the field and laboratory at the International Center for Agricultural Research in the Dry Areas (ICARDA) during the 2005/2006 cropping season. Only two resistance genes (H25 and H26) were effective against the Syrian Hessian fly population, making it the most virulent worldwide. This high virulence supports the hypothesis that Hessian fly coevolved with wheat in the Fertile Crescent of West Asia. The ICARDA screening programme is using this Hessian fly population to identify new resistance genes to this pest.     

The effect of temperature on the development of thepredator Rhyzobius lophanthae and its phenologyin Greece

The effect of temperature on thedevelopment of Rhyzobius lophanthae Blaisdell(Coleoptera: Coccinellidae) fed on Aspidiotusnerii Bouché (Homoptera: Diaspididae) undercontrolled laboratory conditions was studied. Theduration of each developmental stage and adultlongevity were measured at 15, 20, 25, and30 °C. The life cycle of R. lophanthae(from egg to oviposition) lasted 78.7, 43.6, 32.1, and 23.9 days, whereas theaverage adult longevity was 257.6, 171.4, 121.3, and88.5 days at each temperature, respectively. Lowtemperature thresholds of R. lophanthae immaturelife stages ranged from 7.6 to 9.3 °C, while thethermal constant for the development of R. lophanthaefrom egg to adult was 443.5 degree-days. The average fecundity at 25 °C was633.7 eggs per female. Rhyzobius lophanthaereared in cages outdoors during 1993–1995 at Kifissia,Athens developed 5 complete overlapping generationsper year from May to October and a 6th partialoverlapping generation during February and March.Adults of the 4th and 5th generation survived winterconditions giving rise to the following year's 1stgeneration. Females were reproductively activethroughout the year, indicating that R.lophanthae does not diapause.     

Relative risk of invasive ants (Hymenoptera: Formicidae) establishing in New Zealand

Abstract

Human‐assisted spread of species poses a major challenge to border security agencies. Ideally, limited resources need to be targeted at species posing the most risk. Climate matching is an important component of assessing risk but often little or no biological information is available to enable detailed modelling. To assess if distribution records alone provide useful establishment predictions we compare the climate in New Zealand and its outlying islands to that found in the current native and introduced ranges of 12 tramp ant species, three of which are already established in New Zealand, using the climate module of BIOSECURE, a risk assessment tool. Eleven species showed a similar general pattern, with mean annual temperature being the climatic variable with the least overlap between the estimated realised niche and the predicted New Zealand niche. The twelfth species, of temperate origin, is less restricted by temperature, but much of New Zealand may have too high a rainfall. The present and future threats posed by tramp ants are discussed in relation to climate limitations.     

Osmoregulatory capacity,health status and growth as functions of moult stages from various weight classes in marron (Cherax cainii) and yabbies (Cherax destructor)

The study investigated the relationship between five moult stages and the osmoregulatory capacities (OC), moisture content of hepatopancreas (HM%), hepatosomatic indices (HI_wet, HI_dry) and growth of 6 weight classes of 235 marron (Cherax cainii) and 235 yabbies (Cherax destructor) under laboratory conditions. In each moult stage, OC increased linearly with the increase in wet body weight. Intermoult stage C showed the highest OC significantly lower than premoult stages D₀, D₁, D₂ and postmoult stage AB in every weight class in both crayfish. HM% decreased from AB to D₂, while both HI_wet and HI_dry reduced from C to D₂. Percentage dry matter of whole body carcass was highest in stage C and lowest during the AB stage with a significant difference between the two species. Larger than 15-g marron and yabbies differ with each other in OC, HI_wet, and HI_dry, moult intervals and growth rates.     

抗病高干特异资源材料徐781的特性鉴定和亲本利用评价

通过对引自国际马铃薯中心的甘薯实生种子、高代品系进行生产力、抗病性、品质分析等性状的全面鉴定,筛选出抗病高干特异资源材料徐781,并对其不孕群别、砧木适合性、遗传特点等进一步评价,结果表明徐781具有与国内常用亲本亲缘关系远、高干率、高抗茎线虫病、易开花、结实率高、后代入选率高等特点,是国内现有育种材料中罕见的很有利用价值的优异育种材料。     

Genes encoding a group of related small secreted proteins from the gut of Hessian fly larvae [Mayetiola destructor （Say）]

A group of related genes has been isolated and characterized from the gut of Hessian fly larvae [Mayetiola destructor （Say）]. Members in this group appear to encode proteins with secretary signal peptides at the N-terminals. The mature putative proteins are small, acidic proteins with calculated molecular masses of 14.5 to 15.3 kDa, and isoelectric points from 4.56 to 4.88. Northern blot analysis revealed that these genes are expressed predominantly in the gut of Hessian fly larvae and pupae. Two related genes, GIOK1 and GIOK2, were isolated as tandem repeats. Both genes contain three exons and two introns. The intron/exon boundaries were conserved in terms of amino acid encoding, suggesting that they arose by gene duplication. The fact that the frequency of this group of clones in a gut cDNA library higher than that of total cDNA clones encoding digestive enzymes suggested that this group of proteins may perform an important function in the gut physiology of this insect. However, the exact functions of these proteins are as yet known since no sequence similarity could be identified between these proteins and any known sequences in public databases using standard methods.     

钠离子通道与蜜蜂狄斯瓦螨对氟胺氰菊酯的抗性机理

狄斯瓦螨Varroadestructor是全世界蜜蜂最严重的寄生虫 ,目前 ,它对主要防治药物———拟除虫菊酯类的氟胺氰菊酯已产生明显抗性 ,严重影响其防治效果。近年来神经生理学研究结果证实 :电压门控的钠离子通道是拟除虫菊酯作用的位点。钠通道结构的改变 ,是拟除虫菊酯类杀虫剂毒理的主要基础 ,也是产生抗药性的基础。该文介绍了近年来国内外研究电压门控钠离子通道、拟除虫菊酯对钠通道的作用、钠通道与拟除虫菊酯的抗性和狄斯瓦螨对氟胺氰菊酯抗性机理研究的新进展